Herbicidal amides of 4-trifluoromethyl-3&#39;-carboxyl-4&#39;-nitro-diphenyl ethers

ABSTRACT

Compounds of the formula ##STR1## wherein X is a hydrogen atom, a halogen atom, a trihalomethyl group, or an alkyl group, 
     Y is a hydrogen atom or a halogen atom, 
     R 1  is a hydrogen atom, a hydroxy group, an alkoxy group, or an optionally-substituted-alkyl group, and 
     R 2  is a hydrogen atom or an optionally substituted alkyl group, or R 1  and R 2  can be taken together to form a heterocyclic ring, 
     and compositions containing these compounds exhibit herbicidal activity.

This application is a continuation of application Ser. No. 315,103,filed Oct. 26, 1981 which is a continuation of application Ser. No.907,636, filed May 19, 1978, now abandoned.

THE DISCLOSURE

This invention relates to novel compounds which show activity asherbicides, to novel herbicidal compositions which contain thesecompounds, and to new methods of controlling weeds with these herbicidalcompositions.

In accordance with the present invention, there is provided a new classof novel diphenyl ethers having the formula ##STR2## wherein

X is a hydrogen atom, a halogen atom, preferably a fluorine atom or achlorine atom, a trihalomethyl group, preferably a trifluoromethylgroup, or an alkyl group, preferably having 1 to 4 carbon atoms, mostpreferably a methyl group,

Y is a hydrogen atom or a halogen atom, preferably a fluorine atom or achlorine atom,

R¹ is a hydrogen atom, a hydroxy group, a (C₁ -C₄)alkoxy group, an alkylgroup, preferably having 1 to 4 carbon atoms, optionally substitutedwith one or more halogen atoms, hydroxy groups, (C₁ -C₄) alkoxy groups,cyano groups, thiol groups, (C₁ -C₄) alkylthio groups, carboxy groups,or agronomically-acceptable salts thereof, or carb(C₁ -C₄)alkoxy groups,or a cycloalkyl group, preferably having one carbocyclic ring and 5 to 7carbon atoms, and

R² is a hydrogen atom, an alkyl group, preferably having 1 to 4 carbonatoms, optionally substituted with one or more halogen atoms, hydroxygroups, (C₁ -C₄) alkoxy groups, cyano groups, thiol groups, (C₁ -C₄)alkylthio groups, carboxy groups, or agronomically-acceptable saltsthereof, or carb(C₁ -C₄)alkoxy groups, or a cycloalkyl group, preferablyhaving one carbocyclic ring and 5 to 7 carbon atoms, or

R¹ and R² can be taken together with the attached nitrogen atom to forma saturated heterocyclic ring having 4 to 6 carbon atoms and up to oneadditional hetero nitrogen, oxygen, or sulfur atom.

When the X, R¹, or R² substituent is an alkyl group, it can have eithera straight- or branched-chain configuration. When R¹ or R² is asubstituted alkyl group, it will preferably have a single substituent.

These novel compounds have been found to show unexpected activity asweed control agents. In a preferred embodiment of the invention, X is ahalogen atom, most preferably a chlorine atom, Y is a hydrogen atom andR¹ and R² are individually a hydrogen atom or a substituted orunsubstituted (C₁ -C₄)alkyl group, more preferably a hydrogen atom or anunsubstituted (C₁ -C₄) alkyl group. Most preferably either R¹ or R² is ahydrogen atom, and the other an unsubstituted (C₁ -C₄) alkyl group.

Examples of the compounds of the invention embraced by Formula Iinclude:

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N-methylbenzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N,N-diethylbenzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N-t-butylbenbenzamide

2-Nitro-5-(2-bromo-4-trifluoromethylphenoxy)-N-(2-hydroxyethyl)benzamide

2-Nitro-5-(2-fluoro-4-trifluoromethylphenoxy)-N,N-4-oxapentamethylenebenzamide

2-Nitro-5-(2,6-dichloro-4-trifluoromethylphenoxy)-N-methyl-N-(2-hydroxypropyl)benzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N-cyclohexylbenzamide

2-Nitro-5-(2-cyano-4-trifluoromethylphenoxy)-N-carboxymethylbenzamide

2-Nitro-5-(2,4-bistrifluoromethylphenoxy)-N-ethyl-N-(methylthioethyl)benzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N-(2-ethoxyethyl)benzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N-ethylbenzamide

2-Nitro-5-(2-fluoro-4-trifluoromethylphenoxy)-N-methyl-N-(1-carbethoxy)ethylbenzamide

2-Nitro-5-(2-chloro-6-fluoro-4-trifluoromethylphenoxy)-N-methylbenzamide

2-Nitro-5-(4-trifluoromethylphenoxy)-N,N-pentamethylenebenzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N-carboxymethyl-N-(2-hydroxyethyl)benzamide

2-Nitro-5-(2-cyano-4-trifluoromethylphenoxy)benzamide

2-Nitro-5-(4-trifluoromethylphenoxy)-N-(2-cyanoethyl)benzamide

2-Nitro-5-(2-chloro-4-trifluoromethylphenoxy)-N,N'-bis-(2-hydroxyethyl)benzamide

2-Nitro-5-(2-fluoro-4-trifluoromethylphenoxy)-N-hydroxybenzamide

2-Nitro-5-(2,6-dichloro-4-trifluoromethylphenoxy)-N-methoxybenzamide

The novel diphenyl ethers of the invention are useful both aspreemergence and postemergence herbicides. Preemergence herbicides areordinarily used to treat the soil in which the desired crop is to beplanted by application either before seeding, during seeding, or, as inmost applications, after seeding and before the crop emerges.Postemergence herbicides are those which are applied after the plantshave emerged and during their growth period. Compounds of the inventionare particularly active against broadleaf weeds.

Among the crops on which the diphenyl ethers of the invention can beadvantageously employed are, for example, soybeans, peanuts, cotton,corn, wheat, barley, rice and other cereal crops, and the like.

When used in transplanted rice crops, the ethers can be applied eitherpreemergence or postemergence to the weeds--that is, can be applied tothe growth medium of the transplanted plants either before the weedplants have emerged or while they are in their early stages of growth.The ethers can be applied to the growth medium either before or afterthe rice has been transplanted to that medium.

The diphenyl ethers of the invention can be applied in any amount whichwill give the desired degree of weed control. A preferred rate ofapplication of the herbicides of the invention is from about 0.1 to 12,and most preferably about 0.25 to 4, pounds of the diphenyl ether peracre.

Under some conditions, the diphenyl ethers of the invention may beadvantageously incorporated into the soil or other growth medium priorto planting a crop. This incorporation can be carried out by anyconvenient means, including by simple mixing with the soil, by applyingthe diphenyl ether to the surface of the soil and then disking ordragging into the soil to the desired depth, or by employing a liquidcarrier to accomplish the necessary penetration and impregnation.

A diphenyl ether of the invention can be applied to the growth medium orto plants to be treated either by itself or, as is generally done, as acomponent in a herbicidal composition or formulation which alsocomprises an agronomically acceptable carrier. Byagronomically-acceptable carrier is meant any substance which can beused to dissolve, disperse, or diffuse a herbicidal compound in thecomposition without impairing the effectiveness of the herbicidalcompound and which by itself has no detrimental effect on the soil,equipment, crops, or agronomic environment. Mixtures of the diphenylethers of the invention may be used in any of these herbicidalformulations. The herbicidal compositions of the invention can be eithersolid or liquid formulations or solutions. For example, the diphenylethers can be formulated as wettable powders, emulsifiable concentrates,dusts, granular formulations, aerosols, or flowable emulsionconcentrates. In such formulations, the compounds are extended with aliquid or solid carrier and, when desired, suitable surfactants areincorporated.

It is usually desirable, particularly in postemergence applications, toinclude adjuvants, such as wetting agents, spreading agents, dispersingagents, stickers, adhesives, and the like, in accordance withagricultural practices. Examples of adjuvants which are commonly used inthe art can be found in the John W. McCutcheon, Inc. publication"Detergents and Emulsifiers Annual."

The diphenyl ether compounds of this invention can be formulated in anyappropriate solvent. Examples of solvents which are useful in thepractice of this invention include water, alcohols, ketones, aromatichydrocarbons, halogenated hydrocarbons, dimethylformamide, dioxane,dimethyl sulfoxide, and the like. Mixtures of these solvents can also beused. The concentration of the solution can vary from about 2% to about98% with a preferred range being about 25% to about 75%.

For the preparation of emulsifiable concentrates, the diphenyl ether canbe dissolved in organic solvents, such as benzene, toluene, xylene,methylated naphthalene, corn oil, pine oil, o-dichlorobenzene,isophorone, cyclohexanone, methyl oleate, and the like, or in mixturesof these solvents, together with an emulfisying agent which permitsdispersion in water. Suitable emulsifiers include, for example, theethylene oxide derivatives of alkylphenols or long-chain alcohols,mercaptans, carboxylic acids, and reactive amines and partiallyesterified polyhydric alcohols. Solvent-soluble sulfates or sulfonates,such as the alkaline earth salts or amine salts ofalkylbenzenesulfonates and the fatty alcohol sodium sulfates, havingsurface-active properties can be used as emulsifiers either alone or inconjunction with an ethylene oxide reaction product. Flowable emulsionconcentrates are formulated similarly to the emulsifiable concentratesand include, in addition to the above components, water and astabilizing agent such as a water-soluble cellulose derivative or awater-soluble salt of a polyacrylic acid. The concentration of theactive ingredient in emulsifiable concentrates is usually about 10% to60% and in flowable emulsion concentrates, this can be as high as about75%.

Wettable powders suitable for spraying, can be prepared by admixing thecompound with a finely divided solid, such as clays, inorganic silicatesand carbonates, and silicas and incorporating wetting agents, stickingagents, and/or dispersing agents in such mixtures. The concentration ofactive ingredients in such formulations is usually in the range of about20% to 98%, preferably about 40% to 75%. A dispersing agent canconstitute about 0.5% to about 3% of the composition, and a wettingagent can constitute from about 0.1% to about 5% of the composition.

Dusts can be prepared by mixing the compounds of the invention withfinely divided inert solids which may be organic or inorganic in nature.Materials useful for this purpose include, for example, botanicalflours, silicas, carbonates and clays. One convenient method ofpreparing a dust is to dilute a wettable powder with a finely dividedcarrier. Dust concentrates containing about 20% to 80% of the activeingredient are commonly made and are subsequently diluted to about 1% to10% use concentration.

Granular formulations can be prepared by impregnating a solid such as agranular fuller's earth, vermiculite, ground corn cobs, seed hulls,including bran or other grainhulls, or similar material. A solution ofone or more of the diphenyl ethers in a volatile organic solvent is thenremoved by evaporation. The granular material can have any suitablesize, with a preferable size range of 16 to 60 mesh. The diphenyl etherwill usually comprise about 2 to 15% of the granular formulation.

The diphenyl ethers of the invention can also be mixed with fertilizersor fertilizing materials before their application. In one type of solidfertilizing composition in which the diphenyl ethers can be used,particles of a fertilizer or fertilizing ingredients, such as ammoniumsulfate, ammonium nitrate, or ammonium phosphate, can be coated with oneor more of the ethers. The solid diphenyl ethers and solid fertilizingmaterial can also be admixed in mixing or blending equipment, or theycan be incorporated with fertilizers in granular formulations. Anyrelative proportion of diphenyl ether and fertilizer can be used whichis suitable for the crops and weeds to be treated. The diphenyl etherwill commonly be from about 5% to about 25% of the fertilizingcomposition. These compositions provide fertilizing materials whichpromote the rapid growth of desired plants, and at the same time controlthe growth of undesired plants.

The diphenyl ethers of the invention can be applied as herbicidal spraysby methods commonly employed, such as conventional high-gallonagehydraulic sprays, low gallonage sprays, airblast spray, aerial spraysand dusts. For low volume applications a solution of the compound isusually used. The dilution and rate of application will usually dependupon such factors as the type of equipment employed, the methods ofapplication, the area to be treated and the type and stage ofdevelopment of the weeds.

For some applications, it may be desirable to add one or more otherherbicides along with diphenyl ethers of the invention. Examples ofother herbicides which can be incorporated to provide additionaladvantages and effectiveness include:

CARBOXYLIC ACIDS AND DERIVATIVES

2,3,6-trichlorobenzoic acid and its salts

2,3,5,6-tetrachlorobenzoic acid and its salts

2-methoxy-3,5,6-trichlorobenzoic acid and its salts

2-methoxy-3,6-dichlorobenzoic acid and its salts

2,3-dichloro-6-methylbenzoic acid and its salts

2,4-dichlorophenoxyacetic acid and its salts and esters

2,4,5-trichlorophenoxyacetic acid and its salts and esters

2-methyl-4-chlorophenoxyacetic acid and its salts and esters

2-(2,4,5-trichlorophenoxy)propionic acid and its salts and esters

4-(2,4-dichlorophenoxy)butyric acid and its salts and esters

4-(2-methyl-4-chlorophenoxy)butyric acid and its salts and esters

2,3,6-trichlorophenylacetic acid and its salts

3,6-endoxohexahydrophthalic acid dimethyl2,3,5,6-tetrachloroterephthalate trichloroacetic acid and its salts

2,2-dichloropropionic acid and its salts

2,3-dichloroisobutyric acid and its salts

CARBAMIC ACID DERIVATIVES

ethyl N,N-di(n-propyl)thiolcarbamate

propyl N,N-di(n-propyl)thiolcarbamate

ethyl N-ethyl-N-(n-butyl)thiolcarbamate

propyl N-ethyl-N-(n-butyl)thiolcarbamate

2-chloroallyl N,N-diethyldithiocarbamate

N-methyldithiocarbamic acid salts

ethyl 1-hexamethyleneiminecarbothiolate

isopropyl N-phenylcarbamate

isopropyl N-(m-chlorophenyl)carbamate

4-chloro-2-butynyl N-(m-chlorophenyl)carbamate

methyl N-(3,4-dichlorophenyl)carbamate

PHENOLS

dinitro-o-(sec-butyl)phenol and its salts

pentachlorophenol and its salts

SUBSTITUTED UREAS

3-(3,4-dichlorophenyl)-1,1-dimethylurea

3-phenyl-1,1-dimethylurea

3-(3,4-dichlorophenyl)-3-methoxy-1,1-dimethylurea

3-(4-chlorophenyl)-3-methoxy-1,1-dimethylurea

3-(3,4-dichlorophenyl)-1-n-butyl-1-methylurea

3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea

3-(4-chlorophenyl)-1-methoxy-1-methylurea

3-(3,4-dichlorophenyl)-1,1,3-trimethylurea

3-(3,4-dichlorophenyl)-1,1-diethylurea dichloral urea

SUBSTITUTED TRIAZINES

2-chloro-4,6-bis(ethylamino)-s-triazine

2-chloro-4-ethylamino-6-isopropylamino)-s-triazine

2-chloro-4,6-bis(methoxypropylamino)-s-triazine

2-methoxy-4,6-bis(isopropylamino)-s-triazine

2-chloro-4-ethylamino-6-(3-methoxypropylamino)-s-triazine

2-methylmercapto-4,6-bis(isopropylamino)-s-triazine

2-methylmercapto-4,6-bis(ethylamino-s-triazine

2-methylmercapto-4-ethylamino-6-isopropylamino-s-triazine

2-chloro-4,6-bis(isopropylamino)-s-triazine

2-methoxy-4,6-bis(ethylamino)-s-triazine

2-methoxy-4-ethylamino-6-isopropylamino-s-triazine

2-methylmercapto-4-(2-methoxyethylamino)-6-isopropyamino-s-triazine

DIPHENYL ETHER DERIVATIVES

2,4-dichloro-4'-nitrodiphenyl ether

2,4,6-trichloro-4'-nitrodiphenyl ether

2,4-dichloro-6-fluoro-4'-nitrodiphenyl ether

3-methyl-4'-nitrodiphenyl ether

3,5-dimethyl-4'-nitrodiphenyl ether

2,4'-dinitro-4-trifluoromethyldiphenyl ether

2,4-dichloro-3'-methoxy-4'-nitrodiphenyl ether

2-chloro-4-trifluoromethyl-3'-ethoxy-4'-nitrodiphenyl ether

2-chloro-4-trifluoromethyl-4'-nitrodiphenyl ether

2-chloro-4-trifluoromethyl-3'-carbethoxy-4'-nitrodiphenyl ether

2,4-dichloro-3'-carbomethoxy-4'-nitrodiphenyl ether

ANILIDES

N-(3,4-dichlorophenyl)propionamide

N-(3,4-dichlorophenyl)methacrylamide

N-(3-chloro-4-methylphenyl)-2-methylpentanamide

N-(3,4-dichlorophenyl)trimethylacetamide

N-(3,4-dichlorophenyl)-α,α-dimethylvaleramide

N-isopropyl-N-phenylchloroacetamide

N-n-butoxymethyl-N-(2,6-diethylphenyl)chloroacetamide

N-n-methoxymethyl-N-(2,6-diethylphenyl)chloroacetamide

URACILS

5-bromo-3-s-butyl-6-methyluracil

5-bromo-3-cyclohexyl-1,6-dimethyluracil

3-cyclohexyl-5,6-trimethyleneuracil

5-bromo-3-isopropyl-6-methyluracil

3-tert-butyl-5-chloro-6-methyluracil

NITRILES

2,6-dichlorobenzonitrile diphenylacetonitrile

3,5-dibromo-4-hydroxybenzonitrile

3,5-diiodo-4-hydroxybenzonitrile

OTHER ORGANIC HERBICIDES

2-chloro-N,N-diallylacetamide

N-(1,1-dimethyl-2-propynyl)-3,5-dichlorobenzamide maleic hydrazide

3-amino-1,2,4-triazole monosodium methanearsonate disodiummethanearsonate

N,N-dimethyl-α,α-diphenylacetamide

N,N-di(n-propyl)-2,6-dinitro-4-trifluoromethylaniline

N,N-di(n-propyl)-2,6-dinitro-4-methylaniline

N,N-di(n-propyl)-2,6-dinitro-4-methylsulfonylaniline

O-(2,4-dichlorophenyl)-O-methyl-isopropylphosphoramidothioate

4-amino-3,5,6-trichloropicolinic acid

2,3-dichloro-1,4-naphthoquinone di(methoxythiocarbonyl)disulfide

3-isopropyl-1H-2,1,3-benzothiazidzin-(4)3H-one-2,2-dioxide

6,7-dihydrodipyrido[1,2-a:2',1'-c]pyrazidinium salts

1,1'-dimethyl-4,4'-bipyridinium salts

3,4,5,6-tetrahydro-3,5-dimethyl-2-thio-2H-1,3,5-thiadiazine.

4-Amino-6-(1,1-dimethylethyl)-3-methylthio-1,2,4-triazin-5-(4H)-one

3-Amino-2,5-dichlorobenzoic acid

N³, N³ -Diethyl-2,4-dinitro-6-trifluoromethyl-1,3-phenylene-diamine

N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-trifluoromethylaniline

N-Cyclopropylmethyl-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine

N-(1-Ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzeneamine

S-(O,O-diisopropyl)phosphorodithioate ester ofN-(2-mercaptoethyl)benzenesulfonamide

2(α-Naphthoxy)-N,N-diethylpropionamide

2-Chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide

Methylsulfanilylcarbamate

3-(p-(p-Chlorophenoxy)phenyl)-1,1-dimethylurea

Phosphonomethylglycine

Methyl 2-(4-(2,4,-dichlorophenoxy)phenoxy)propionate

Sodium 2- 4-[(3,5-dichloro)-2-pyridyloxy]phenoxy propionate

Methyl 2-(4-(4-trifluoromethylphenoxy)phenoxy)propionate

When mixtures of herbicides are employed, the relative proportions whichare used will depend upon the crop to be treated and the degree ofselectivity in weed control which is desired.

The ethers of the invention can be prepared by reacting an acid halide,preferably an acid chloride of a diphenyl ether of the formula ##STR3##wherein X and Y are as defined above, with an excess of an amine of theformula

    HNR.sup.1 R                                                (III)

wherein R¹ and R² are as defined above. This reaction is generallycarried out in a solvent in which the acid chloride is soluble, such asdiethyl ether, a chlorinated hydrocarbon, an aromatic hydrocarbon, orthe like, at a temperature of about 0° to about 100° C., preferably atabout 0° to about 40° C. The amination reaction can also be carried outunder Schotten-Bauman conditions, where one equivalent of an amine ofFormula III is first added to a mixture of an organic solvent, such asdiethyl ether or the like, and an aqueous solution of a strong inorganicbase, such as sodium hydroxide, or the like, followed by the slowaddition of an organic solution of the acid chloride, for example intoluene, to the agitated two-phase system. This reaction is generallycarried out at a temperature of about 0° to about 100° C., preferablyabout 10° to about 40° C.

Compounds of the invention can also be prepared by reacting an ester ofa diphenyl ether of Formula II with an amine of Formula III, using anacid catalyst, such as p-toluenesulfonic acid, hydrochloric acid,sulfuric acid or the like in a suitable inert solvent, such astetrahydrofuran, glyme, toluene, xylene, or the like, at a temperatureof about 20° to the reflux temperature of the solvent. In another routeto the compounds of the invention, an ammonium salt of a diphenyl etherof Formula II, in which the cation has the formula

    ⊕NH.sub.2 R.sup.1 R.sup.2                              (IIIa)

wherein R¹ and R² are as defined above, is heated at a temperature ofabout 100° to about 200° in a high-boiling inert solvent, such astoluene, xylene, diglyme, or the like, to produce the amide directly.

The diphenyl ether precursors can be prepared by reacting a suitablysubstituted phenol, or the potassium or sodium salt of the phenol, witha suitably substituted halobenzene, such as a chloro- or fluorobenzenein the presence of an alkaline agent. Such precursors and theirpreparation are described in U.S. Pat. No. 3,928,416, Bayer et al.,granted Dec. 23, 1975, and U.S. Pat. No. 4,031,131, of Johnson, grantedJune 21, 1977, which are incorporated herein by reference.

Another route to the compounds of the invention involves the nitrationof a diphenyl ether of the formula ##STR4## wherein X, Y, R¹ and R² areas defined above, using typical nitrating agents such as potassiumnitrate in sulfuric acid, acetyl nitrate, mixed sulfuric acid/nitricacid, nitrosonium tetrafluoroborate, and the like. The nitrationreaction is generally carried out at about 20° to about 100° C.,preferably about 0° to about 5° C., optionally in the presence of aninert organic solvent, such as methylene chloride or other chlorinatedhydrocarbon.

Amides of the invention can also be prepared by condensing a phenol ofthe formula ##STR5## wherein X and Y are as defined above with asubstituted halobenzene of the formula ##STR6## wherein X¹ is a halogenatom, preferably a fluorine atom, and R¹ and R² are as defined above.This reaction is generally carried out at a temperature of about 0° toabout 250° C., preferably about 75° to about 200° C., optionally in thepresence of an appropriate solvent, such as sulfolane,dimethylsulfoxide, dimethylformamide, hexamethylphosphorustriamide, orother inert polar organic solvent.

The following examples will further illustrate this invention but arenot intended to limit it in any way. In Table I, typical diphenyl ethersof the invention are listed with their elemental analyses. A specificillustrative preparation of the compound of Example 2 is set forthbefore Table I. All temperatures are in degrees Celsius and parts andpercentages are by weight unless otherwise indicated.

EXAMPLE 2 EXPERIMENTAL Preparation of2-nitro-5-(2-chloro-4-trifluoromethylphenoxy-N-methylbenzamide

A solution of 2-nitro-5-(2-chloro-4-trifluoromethylphenoxy)benzoylchloride (10 g., 0.026 mole) and an excess of methylamine was stirred atroom temperature in toluene for five hours. Amine hydrochloride wasfiltered off and the filtrate stripped to yield2-(nitro-5-(2-chloro-4-trifluoromethylphenoxy)benzoyl chloride (8 g.)m.p. 118°-120° C.

                                      TABLE I                                     __________________________________________________________________________    Diphenyl Ethers - Physical Data                                                ##STR7##                                                                     Example                                                                       No.  R.sup.1                                                                          R.sup.2                                                                          m.p. (°C.)                                                                        % C                                                                              % H % N                                                                              % Cl                                                                              % F                                       __________________________________________________________________________    1    H  H  m.p. 139-143                                                                         Found                                                                             45.77                                                                            2.30                                                                              7.91                                                               reqs                                                                              46.62                                                                            2.23                                                                              7.76                                             2    Me H  m.p. 118-120                                                                         Found                                                                             47.41                                                                            2.87                                                                              6.96                                                                             9.32                                                                              14.45                                                       reqs                                                                              48.08                                                                            2.69                                                                              7.49                                                                             9.46                                                                              15.21                                     3    Et H  m.p. 120-122                                                                         Found                                                                             49.49                                                                            3.14                                                                              7.02                                                                             9.17                                                                              14.51                                                       reqs                                                                              49.44                                                                            3.11                                                                              7.21                                                                             9.12                                                                              14.66                                     4    Me Me oil    Found                                                                             48.13                                                                            3.49                                                                              6.87                                                                             11.64                                                                             14.75                                                       reqs                                                                              49.44                                                                            3.11                                                                              7.21                                                                             9.12                                                                              14.66                                     5    Et Et m.p. 75-90                                                                           Found                                                                             50.26                                                                            3.84                                                                              6.04                                                                             9.94                                                                              13.90                                                       reqs                                                                              51.80                                                                            3.88                                                                              6.73                                                                             8.55                                                                              13.68                                     6    i-Pr                                                                             H  m.p. 135-137                                                                         Found                                                                             55.19                                                                            4.47                                                                              7.49                                                                             9.24                                                                              15.07                                                       reqs                                                                              54.77                                                                            4.32                                                                              7.51                                                                             9.51                                                                              15.28                                     __________________________________________________________________________

The following examples show the herbicidal properties of diphenyl ethersof the invention.

EXAMPLE 6

This example shows the herbicidal activity of diphenyl ethers of theinvention towards a number of common weeds. Using the proceduredescribed below, diphenyl ethers are evaluated for control of variousplant species.

The following test procedure is employed. Seeds of selected crops andweeds are planted in soil in trays. For preemergence tests, the traysare treated with the test compound immediately after the planting. Forpostemergence tests, the seeds are allowed to germinate, and after twoweeks the trays are treated with the test compound immediately after theplanting. The compound to be evaluated is dissolved in acetone, dilutedwith water, and sprayed over the trays using a carrier volume equivalentto 50 gallons per acre at the rate of application of two or four poundsper acre. About two weeks after the application of the test compound,the state of growth of the plants is observed and the phytotoxic effectof the compound is evaluated. The results of typical tests aresummarized in Table II, which gives the average percent control achievedby the test compounds with 0 representing no weed control and 100complete kill of the plant.

The following species were tested:

    ______________________________________                                        Monocots                                                                      barnyardgrass     Echinochloa crusgalli                                       downybrome        Bromus tectorum                                             green foxtail     Setaria vividis                                             johnsongrass      Sorghum halepense                                           yellow nutsedge   Cyperus esculentus                                          wild oats         Avena fatua                                                 Dicots                                                                        cocklebur         Xanthium pensylvanicum                                      marigold          Tagetes patula                                              tomato            Lycopersicum esculentum                                     morningglory      Ipomoea sp                                                  nightshade        Solanum nigrum                                              velvetleaf        Abutilon theophrasti                                        safflower         Carthamus tinctorius                                        ______________________________________                                    

                                      TABLE II                                    __________________________________________________________________________    Greenhouse Weed Control Data                                                            Monocot                   Dicot                                               Barn-    Green                                                                             Johnson-                                                                            Yellow             Morn-   Vel-                  Compound of                                                                             yard-                                                                             Downy-                                                                             fox-                                                                              grass nut-                                                                              Wild                                                                             Cockle-                                                                            Mari-                                                                             To-                                                                              ing-                                                                              Night-                                                                            vet-                                                                             Saf-               Example No.                                                                          lb/A                                                                             grass                                                                             brome                                                                              tail                                                                              (seedlings)                                                                         sedge                                                                             oats                                                                             bur  gold                                                                              mato                                                                             glory                                                                             shade                                                                             leaf                                                                             flower             __________________________________________________________________________    1  Pre 2  99  60   100 100   99  30 70   --  -- 70  100 60 0                     Post                                                                              2  70  50   70  90    40  40 100  --  -- 95  100 100                                                                              80                 2  Pre 2  99  40   100 99    100 95 80   100 100                                                                              90  --  99 --                    Pre 4  100 95   100 100   100 95 80   100 100                                                                              80  --  95 --                    Post                                                                              2  90  30   100 70    100 30 70   99  95 60  --  100                                                                              --                    Post                                                                              4  90  20   95  30    50  40 70   70  40 70  --  95 --                 3  Pre 2  99  20   100 99    80  99 0    100 100                                                                              80  --  100                                                                              --                    Pre 4  100 40   100 99    99  95 60   100 100                                                                              95  --  100                                                                              --                    Post                                                                              2  70  20   99  40    60  20 60   95  90 80  --  90 --                    Post                                                                              4  80  70   100 60    99  50 60   95  60 60  --  80 --                 4  Pre 2  95  50   99  50    20  30 0    100 70 10  --  80 --                    Pre 4  99  70   100 90    95  95 0    100 100                                                                              40  --  100                                                                              --                    Post                                                                              2  40  0    80  30    80  20 90   99  100                                                                              90  --  100                                                                              --                    Post                                                                              4  50  20   95  20    60  20 80   99  90 60  --  100                                                                              --                 5  Pre 4  40  0    80  50    0   0  0    -   -- 0   0   0  0                     Post                                                                              4  0   0    0   0     0   0  40   --  -- 10  30  30 30                 __________________________________________________________________________     -- indicates not tested                                                  

EXAMPLE 7

This example shows the selectivity of the diphenyl ethers of theinvention towards several common crops, including corn, cotton, rice,soybeans and wheat. Using a procedure similar to Example 6, thefollowing crops were planted and treated--corn, cotton, rape, rice,sugarbeet, soybeans and wheat. The results of typical tests aresummarized in Table III, which gives the average percent injury causedby the test compound with 0 representing no injury and 100 complete killof the plant.

                                      TABLE III                                   __________________________________________________________________________    Compound of                                                                             Preemergence          Postemergence                                 Example No.                                                                          lb/A                                                                             CN COT                                                                              RA RI SB SOY                                                                              WHT CN COT                                                                              RA RI SB SOY                                                                              WHT                         __________________________________________________________________________    2 NHMe 2  80 0  100                                                                              30 100                                                                              50 15  5  80 80 20 80 40 5                                  1  15 0  100                                                                              20 100                                                                              20 10  5  60 90 10 80 20 10                                 1/2                                                                              20 0  100                                                                              15 100                                                                              0  10  5  60 80 20 80 20 5                           3 NHEt 2  30 0  100                                                                              10  90                                                                              0  20  5  30 80 15 50 20 5                                  1  10 0  100                                                                              20 100                                                                              0  10  0  30 80 15 50 10 0                                  1/2                                                                               0 0  100                                                                              10  95                                                                              0  10  0  40 70 10 45 10 5                           4 NMe.sub.2                                                                          2   0 0  100                                                                              10  95                                                                              0  10  5  35 70 10 65 10 5                                  1  10 0  100                                                                              10  90                                                                              0   0  0  25 70  5 70 10 5                                  1/2                                                                              10 0   95                                                                              10  70                                                                              0   0  0  25 70  5 50 15 5                           5 NEt.sub.2                                                                          2   0 0  100                                                                               0 100                                                                              0   5  15 30 80  5 60 10 10                                 1   0 0   95                                                                               0  95                                                                              0   5  15 30 80  5 50 15 15                                 1/2                                                                               0 0   80                                                                               0  90                                                                              0  10  20 20 70  0 55 10 5                           __________________________________________________________________________

It is to be understood that changes and variations can be made withoutdeparting from the spirit and scope of this invention as defined by theappended claims.

I claim:
 1. A compound of the formula ##STR8## wherein X is a hydrogenatom, a halogen atom, a (C₁ -C₄)alkyl group, or a trifluoromethylgroup,Y is a hydrogen atom or a halogen atom, R¹ is a hydroxy group, a(C₁ -C₄)alkoxy group, and R² is a (C₁ -C₄)alkyl group, optionallysubstituted with a halogen atom, a hydroxy group, a (C₁ -C₄)alkoxygroup, a cyano group, a thiol group, a (C₁ -C₄)alkylthio group, acarboxy group, or an agronomically-acceptable salt thereof, or a carb(C₁-C₄)alkoxy group, or a monocyclic (C₅ -C₇)cycloalkyl group.
 2. Thecompound of claim 1 wherein R² is an unsubstituted (C₁ -C₄)alkyl group.3. A herbicidal composition which comprises a compound according toclaim 1 and an agronomically-acceptable carrier.
 4. The composition ofclaim 3 which additionally comprises a surfactant.
 5. A method ofcontrolling weeds which comprises applying to the surface of the growthmedium prior to the emergence of the weeds frm the growth medium orapplying to weed seedlings a compound of claim 1 in an amount effectiveto control the growth of the weeds.
 6. The method of claim 5 wherein thecompound is applied in an amount of about 0.1 to about 12 pounds peracre.
 7. A method for selectively controlling weeds in an agronomic cropwhich comprises applying to the area in which the crop is growing or isto be grown a compound of claim 1 in an amount sufficient to control thegrowth of the weeds without significantly affecting the growth of theagronomic crop.
 8. The method of claim 7 wherein the crop is corn,cotton, rice, soybeans, or wheat.